VI 



PAGE. 



Soft Limestone : Chalk 26 



Origin and General Characters '...'.'. 26 



Geographical and Geological Distribution in the 



United States 26 



Composition 27 



Fresh Water Marls 27 



Origin of Marls 28 



Geographical Distribution of Marl Deposits 29 



Composition 9<* 



Alkali Waste 30 



Blast Furnace Slag 31 



Clays and Shales 32 



Slate 33 



CHAPTER V. 



Economic Considerations and Methods of Manufacture 34 



Quarrying 34 



Mining . 35 



Dredging 35 



Cost of the Raw Material at Mill 36 



Methods of Manufacture 38 



Preparation of the Mixture for the Kiln 38 



Drying the Raw Materials 39 



Percentage of Water in the Raw Material 39 



Methods and Cost of Drying 40 



Grinding and Mixing Dry Methods 41 



Fineness of Mixture 42 



Grinding and Mixing Slag-limestone Mixtures 43 



General Methods 43 



Composition of the Slag 44 



Granulation of the Slag 44 



Drying of the Slag 45 



Grinding the Slag 45 



Composition of the Limestone 45 



Economics of using Slag-umestone Mixtures. ... 46 



Grinding and Mixing Wet Methods 47 



Composition of the Mixture 4 



Burning the Mixture 50 



Summary of Burning Process 51 



Theoretical Fuel Requirements 52 



Losses of Heat in Practice 52 



Actual Fuel Requirements and Output 53 



Effect of Composition on Burning 54 



Character of Kiln Coal 54 



Drying Coal 55 



Pulverizing Coal 55 



Total Cost of Coal Preparation 55 



Clinker Grinding: Gypsum 56 



Clinker Grinding 56 



Addition of Gypsum 57 



Constitution of Portland Cement 57 



